The present invention relates to a color filter assembly for use with a stage lighting to produce a variable lighting effect.
It has been well known that putting different color filter lenses or different light tight objects having variously shaped through holes in the passage of the light of a light source, can change the color or projecting pattern of the light. Examples of the applications of these techniques have been seen in U.S. Pat. No. 5,283,723 under the title of "Backward Projection Type Wall Lamp" and U.S. Pat. No. 5,163,749 under the title of "Wall Lamp With Refraction Lenses". The common drawback of these wall lamps is that they can only produce a fixed lighting pattern.
FIG. 1 shows an arrangement of a stage lighting which produces a variable lighting effect.
The arrangement includes a light source (high power lamp), a reflector and a fan aligned at the right side, and a rotary color filter wheel aligned at the left side. The light of the light source is reflected onto the color filter wheel by the reflector, and then reflected in different directions by a spherical reflecting mirror. The color filter wheel has a plurality of gratings disposed at different locations. When the color filter wheel is turned, the gratings pass through the passage of the light one after another, causing the pattern of light changed alternatively. At the same time, the spherical reflecting mirror is turned to reflect the light in different directions. Because the color filter wheel and the motor drive, which drives the color filter wheel, are both installed in the passage of the light, they constantly receive the heat of the light source causing their service life shortened. Another drawback of this arrangement is that the gratings of the color filter wheel are not changeable. As the light of the light source filtrated through the color filter wheel and then reflected by the spherical reflecting mirror, the intensity of the light is attenuated.